Cancer is one of the primary causes of death worldwide. Oral cancer, the most common malignancy in the head and neck region, is the eighth most prevalent cancer in the world [1]. Oral malignancies accounts for about 3–4% of all cancers and 2–3% of cancer-related deaths [2]. The predominant malignant neoplasms in the oral cavity are squamous cell carcinomas (SCC), with the tongue and floor of mouth being the most common sites of occurrence. The aetiology of oral cancer is multifactorial with genetic, environmental, social and behavioral factors implicated in its development. It has been projected that nearly 75% of all cancers are due to tobacco or alcohol intake [3]. Evidence from case-control and cohort studies point to a causal association between these two risk factors and oral malignancy [4] [5]. Other risk factors for oral cancer include previous upper aero-digestive tract malignancy, an older age group, human papillomavirus infection, exposure to ultraviolet light, betel quid consumption and iron deficiency anemia.

Oral cancers mainly afflict men, with about 275,000 new cases diagnosed annually and it is associated with a high morbidity and mortality [6] [7][8]. Equally troubling is the fact that the incidence of oropharyngeal cancer among women and younger patients continues to increase due to human papillomavirus (HPV) infection [9][10]. Oral cancer is essentially preventable through avoiding known risk factors and many international guidelines emphasize the importance of early detection [11]. Early detection of oral cancer is possible because it occurs mainly at sites that are visible or easily accessible to a painless and non-invasive examination [1]. Oral cancer is sometimes preceded by noticeable alterations in the oral mucosa like white or red lesions, ulcers or exophytic growths, with no other obvious signs or symptoms. If it is diagnosed and managed at this stage, it is curable and economical to treat with excellent treatment prognosis and outcome [12]. Most patients, however, do not seek medical care until the tumor is advanced with symptoms of persistent pain. Most oral cancer cases are thus detected at advanced stages that require complex and costly treatments which is associated with unfavorable outcomes [13]. Regrettably, the main modality of treatment in patients with oral cancer is surgery and this often leads to aesthetic and functional deformities, with severe impact on their quality of life. For these reasons, oral cancer remains a public health problem.

Irrespective of the risk factors implicated in oral cancer development, the most significant element that modifies patient survival is the stage at which it is detected [14]. In spite of improvements in diagnostic procedures in medical practice, the mortality of oral cancer has remained unchanged and a substantial diagnostic delay has continued over time [15] [16] . Some of the reasons given for this delay include lack of public awareness about the signs, symptoms and risk factors for oral cancer; non-attendance for routine oral examination in the community, absence of symptoms in early stages of the disease; growth of cancer in areas of oral cavity which are not normally inspected by the patients and/or physician and absence of prevention initiatives by heath care providers [15] [16] . A lack of knowledge of oral cancer, its symptoms, and risk factors has also been correlated with late diagnosis and poor prognosis/outcome [3]. The inadequacy of public awareness of the signs, symptoms and risk factors related to oral cancer has been reported [17]. It is possible that improvement in early diagnosis of oral cancer can be achieved by raising the awareness of the population towards seeking dental care upon identification of oral lesions. Only a few studies [18] [19] have been done in Nigeria to determine the level of awareness about oral cancer in Nigeria and there is further need to determine the knowledge of the signs and risk factors for oral cancer as well as attitudes towards oral examination and early diagnosis.

The aim of the study was to determine the awareness level of oral cancer in a group of patients presenting for routine dental care at the Lagos State University Teaching Hospital, Ikeja, Lagos State (LASUTH).

This descriptive and cross-sectional study was conducted at the Oral Diagnosis Clinic of the Lagos State University Teaching Hospital, Ikeja, Lagos State (LASUTH).

Sample selection
The study sample consisted of routine patients that presented for care at the Oral diagnosis clinic of LASUTH. A simple random sampling technique using the balloting method was used to determine the study participants using the attendance register for each clinic day as the sampling frame. Selected participants were screened for eligibility by set inclusion and exclusion criteria and those that met these criteria and were ready to give their informed consent were enlisted into the study.

Sample size
The sample size was calculated using a formula for cross sectional studies: n = Z pq/d². where n= Sample size;
Z = Standard normal Deviate (1.96)
p= prevalence value from reference study.
q= 1-p

Using the prevalence of 72% for level of awareness from a reference study [18], a sample size of 77 was determined. One hundred respondents were, however, recruited during the study period.

Study Setting and location
This study was done at Oral Diagnosis clinic of the Lagos State University Teaching Hospital, (LASUTH), Ikeja, Lagos, Nigeria. Lagos State University Teaching Hospital is a tertiary health facility situated in the capital of Lagos State. It is a multi-specialist hospital with a bed complement of 741. The oral diagnosis clinic is the first point of contact with patients in the dental facility of the hospital after their registration and an average of 30 patients are seen at the oral diagnosis clinic on each day.

Inclusion and Exclusion criteria
Patients included in the study were those that were presenting at the clinic for the first time and were above 18 years old. Patients that were excluded from the study were those that were previously registered for care at the dental clinic and had undergone a session of oral health education and those that had features that were suggestive of malignancy.

Ethical aspects
All the study participants completed a written informed consent form which contained names and affiliation of investigators and a plain language description of the study. The study was based on questionnaire which did not involve any clinical examination nor any form of intervention.

Data collection
A 31-item structured interviewer administered closed-ended questionnaire in English language was used for data collection. The structured self-administered questionnaire was adapted from a previous study [20] and it had three sections. The first part of the questionnaire obtained the socio-demographic information of the respondents such as age, gender, marital status, level of education, and ethnicity. The second section of the questionnaire obtained the medical and dental history of the respondents while the third section recorded their responses to questions on the risk factors for oral cancer.

Data analysis
The data obtained was analyzed using the statistical package for social sciences (SPSS version 20). Categorical variables were summarized as frequencies and percentages. The level of knowledge of oral cancer was assessed among the respondents was rated and each correctly answered question earned one mark giving a maximum obtainable score of 15. Scores 0–7 were graded as inadequate knowledge on oral cancer while scores 8 and above were graded as adequate knowledge on oral cancer. Statistical significance for association between variables was assessed using chi-square statistical test. Level of significance in this study was set at 0.05 or lower than this value.

The sample of 100 patients comprised of 61 (61%) female subjects and 39(39%) male subjects. Most of the respondents were between 18–34 years of age (43%), were married (53%) and had a tertiary level of education (78%) (Table 1).

Sixty-six percent of participants had heard about oral cancer and the public media (television, newspapers, and radio) were the main sources of information (76%). Only 3% had heard about oral cancer from their dentists, while 10% had heard about it from their Doctors. Most of the respondents (10%) obtained health advice from a physician, while only 10% said they obtained health advice from a dentist. Other sources of health information mentioned included the newspapers, television, the Church and Health Centers (Table 2).

Only 3% of respondents were current smoker while 6% had previously smoked or were currently smoking. About 5% reported past use of smokeless tobacco, chewing tobacco or snuff while none of the respondents was presently using smokeless tobacco. Twenty-nine percent of the respondents reported drinking alcohol currently while 45% had a history of past and present consumption. The majority of respondents (31%) said they had seen a dentist within the previous six months and that the dentist enquired about their use of tobacco (72%) and alcohol (86%). Only 9% of respondents had been vaccinated for HPV (Table 3).

Eighty-two percent of the respondents had never had about an oral cancer examination while only 7% of them were sure they had received a tongue examination for oral cancer. Majority of the respondents (65%) had not had the examination because they were never informed of the need for it. Forty-four percent of the sample felt that a dentist's recommendation was required for an examination (Table 4).

When asked who they would see if they found a "lump" in their mouth, 59% said they would see a dentist while 33% said they would see a doctor. Most of the sample (97%) was willing to have a free oral cancer examination but felt that the community centre should be the site of the examination (Table 5).

The risk factors that were correctly identified by majority of the respondents in the development of oral cancers were cigarettes smoking (72%); smoking marijuana (73%); chewing tobacco or using snuff (63%); HPV infection (55%); smoking local cigarettes (42%); alcohol consumption (42%), and oral sex (45%). Only 28% of the respondents had a high knowledge of the risk factors for oral cancer (Table 6).

Older patients (>35 years of age) (p = 0.013), those that were married (p = 0.009) and secondary school educated respondents (p = 0.001) had a significantly lower level knowledge about the risk factors of oral cancer (Table 7).

Respondents that saw a dentist (p = 0.043) or their medical doctor (p = 0.000) within six months to three years had significantly higher knowledge of oral cancer risk factors than those who had never had a visit or who visited more than three years ago. Similarly, the participants whose dentists (p = 0.012) or medical doctors (p = 0.003) enquired about tobacco use had significantly higher knowledge of oral cancer risk factors. Respondents that had been vaccinated against HPV also had a significantly higher knowledge (p = 0.038) than those who had not been vaccinated or were not sure (Table 8).

The study participants that had heard of oral cancer (p = 0.027) and those that had had an oral cancer examination (p = 0.022) had significantly higher knowledge of the risk factors for oral cancer. Respondents who have never smoked were also significantly more likely to have high knowledge of the risk factors of oral cancer (p = 0.011). Similarly, those who rarely or do not consume alcohol also had a significantly higher knowledge of the risk factors (p = 0.005) (Table 9).

The present study examined the level of awareness and knowledge about oral cancer in dental patients in LASUTH. Majority of the subjects were female, between 18–34 years of age, and had a tertiary level of education possibly indicating a higher level of health seeking behavior among females and highly educated patients. The level of participants' awareness about oral cancer was average, with only about 66% of them knowing about oral cancer. Research has demonstrated that nations with a high prevalence of oral cancer, such as India, Sri Lanka, and Malaysia had a greater level of community awareness about the condition [21] [22][23] which was in contrast to the low level of awareness in a country with a low prevalence [24]. However, only 3% of the respondents in the index study heard about oral cancer from their dentist while 10% received the information from their physicians. This was similar to the observation made by Lawoyin et al. [18] in a previous Nigerian study where only 20.1% of patients heard about oral cancer from health professionals.

The public media such as television, newspapers and radio were the main sources of information for those who had heard. Even though more than 70% of the dentists obtained information about tobacco and alcohol use from the respondents, only a few educated them about oral cancer or linked the use of alcohol and tobacco use with the development of oral malignancy. They thus missed an opportunity to provide a one-on-one education to link the risk factors of oral cancer to the development of the disease. Previous studies have shown that the public lack knowledge that an oral cancer examination exists, and do not ask for it and that there is an increase in the number of patients requesting for oral cancer examination once it is described to them [20]. This may indicate that dental surgeons are doing oral cancer examinations without educating their patients about it [25]. This indicates that the public is not properly informed about the risk factors for oral cancer, the importance of oral examination, and the significance of early detection [26]. Dental surgeons have an important role to offer counseling on the prevention of oral cancer. Similarly, patients attending the dental clinic for treatments unrelated to oral cancer can be incorporated into a preventive recall schedule if they are observed to be in the high risk category [27].

Unlike 29% of the respondents who admitted to alcohol consumption and 45% with a history of past and present use of alcohol, only 3% and 6% of the respondents admitted to present or past history of tobacco smoking respectively. This is lower than the prevalence for smoking in the general population in Nigeria which is estimated at 8.9%. Some segments of the Nigerian population, however, have higher prevalence which is as high as 37.9% in Northern Nigeria [28]. The lower prevalence recorded in the index study could be due to deliberate recall bias on the part of the participants because of the social undesirability of cigarette smoking in Nigeria or to the higher percentage of female respondents who are known to smoke less in Nigeria. Tobacco consumption is the most important modifiable cancer risk and about 30% of all cancers in developed countries are tobacco-related [29]. A previous study had observed that medical doctors are twice more likely to initiate tobacco smoking cessation for their patients than dentists [30]. Tobacco use cessation should be encouraged in dental clinics to reduce the effect of this major risk factor for oral and systematic diseases.

Furthermore, 82% of the respondents had never heard of an oral cancer examination and only 7% of them were sure they had received a tongue examination for oral cancer. Majority of the respondents had not had the examination because they were never informed of the need for it by their dentist or physician. Only over half of the respondents also felt they needed to see their dentist if they had a lump in their mouth. In spite of improvements in treatment modalities over past decades, a significant change in the prognosis of oral cancer has not achieved. This is possibly due to the failure to identify small and potentially malignant lesions early, which precludes successful treatment. Therefore, early detection is the key to improve survival rate in oral cancer patients [31]. The mortality associated with oral cancer can be reduced by clinical examination. One study described a 32% decline in mortality in high risk individuals, thus implying that about 40000 deaths can be prevented by oral examination worldwide [32].

Correspondingly, Only 28% of the respondents had a high knowledge of the risk factors for oral cancer even though majority of them correctly identified tobacco smoking as a risk factor. It is surprising that only 42% of the respondents were aware that alcohol was a risk factor and this is significant when one observes a higher level of alcohol consumption than cigarette smoking in the study population. The better awareness of tobacco as a risk factor can be ascribed to the public health messages associated with cigarettes sales packages and anti-tobacco advocacy by many groups in the country. Similar allocation of resources and effort to enlighten the public about the association between alcohol consumption and its synergistic effect with tobacco in the development of oral cancer is required to reverse this trend. Awareness of all the risk factors and symptoms of oral cancer could thus lead to early clinical presentation and a reduction in morbidity and mortality associated with this condition [33].

The results of the present study showed that older respondents had a lower awareness about the risk factors of oral cancer. This can be adduced to fact that the mass media which the youth are more exposed to was the most common source of information. This is disheartening because the older participants who are more at risk due to age are less knowledgeable. Participants with a university education also had a significantly higher knowledge about the risk factors of oral cancer, a finding consistent with the results of other studies [34] [35]. Interestingly, high-risk groups, such as male subjects, smokers, alcohol drinkers, and participants >40 years of age, had much less knowledge about the risk factors and signs of oral cancer. Improving knowledge of these high-risk groups about oral cancer is therefore particularly important.

Regular dental attendance and positive health habits also appeared to be positively associated with knowledge of the risk factors of oral cancer. Respondents that saw a dentist or their medical doctor within six months to three years and those that had an oral cancer examination had significantly higher knowledge of oral cancer risk factors than those who had never had a visit or who visited more than three years ago. Similarly, the participants whose dentists or medical doctors enquired about tobacco use as well as those who do not smoke and rarely or did not consume alcohol had significantly higher knowledge of oral cancer risk factors. Respondents that had been vaccinated against HPV also had a significantly higher knowledge than those who had not been vaccinated or were not sure. It is thus essential to educate the public, particularly those in the high risk category about oral cancer and to use every dental visit for oral health promotion and opportunistic screening [36] [37].

This study explored the level of awareness and knowledge about oral cancer in dental patients in LASUTH, deficits were observed in the knowledge of the participants on oral cancer and its associated risk factors. The level of knowledge was influenced by socio-demographic characteristics of the respondents, their dental or medical clinic attendance pattern and exposure to health education and cancer screening. A common risk factor approach which incorporates oral cancer information into national health surveillance systems should be explored since the perceived risk of experiencing a disease can modify behavioral responses that can limit its development. Approaches to increase public awareness about oral cancer and continuing professional development for oral health professionals about early detection and diagnosis must also be emphasized. Primary preventive initiatives should similarly be initiated to reduce exposure to these risk factors while every dental visit should be an opportunity to provide information about oral cancer and to do a thorough mouth examination.

1. Petersen PE. Strengthening the prevention of oral cancer: the WHO perspective. Community Dent Oral Epidemiol 2005 Dec;33(6):397–9.   [Pubmed]    
2. Parkin DM, Läärä E, Muir CS. Estimates of the worldwide frequency of sixteen major cancers in 1980. Int J Cancer 1988 Feb 15;41(2):184–97.   [CrossRef]   [Pubmed]    
3. Pinto FR, Matos LL, Gumz Segundo W, Vanni CM, Rosa DS, Kanda JL. Tobacco and alcohol use after head and neck cancer treatment: influence of the type of oncological treatment employed. Rev Assoc Med Bras 2011 Mar-Apr;57(2):171–6.   [CrossRef]   [Pubmed]    
4. Choi SY, Kahyo H. Effect of cigarette smoking and alcohol consumption in the aetiology of cancer of the oral cavity, pharynx and larynx. Int J Epidemiol 1991 Dec;20(4):878–85.   [CrossRef]   [Pubmed]    
5. Kato I, Nomura AM, Stemmermann GN, Chyou PH. Prospective study of the association of alcohol with cancer of the upper aerodigestive tract and other sites. Cancer Causes Control 1992 Mar;3(2):145–51.   [CrossRef]   [Pubmed]    
6. Galbiatti AL, Padovani-Junior JA, Maníglia JV, Rodrigues CD, Pavarino ÉC, Goloni-Bertollo EM. Head and neck cancer: causes, prevention and treatment. Braz J Otorhinolaryngol 2013 Mar-Apr;79(2):239–47.   [CrossRef]   [Pubmed]    
7. Montoro JR, Ricz HA, Souza Ld, et al. Prognostic factors in squamous cell carcinoma of the oral cavity. Braz J Otorhinolaryngol 2008 Nov-Dec;74(6):861–6.   [CrossRef]   [Pubmed]    
8. Casati MFM, Altieri JV, Vergnhanini GS, Contreiro PF, Bedenko TG, Kanda JL. Epidemiologia do câncer de cabeça e pescoço no Brasil: estudo transversal de base populacional. Rev Bras Cir Cabeça Pescoço 2012;41:186–91.    
9. Psyrri A, Gouveris P, Vermorken JB. Human papillomavirus-related head and neck tumors: clinical and research implication. Curr Opin Oncol 2009 May;21(3):201–5.   [CrossRef]   [Pubmed]    
10. zur Hausen H. Papillomaviruses in the causation of human cancers - a brief historical account. Virology 2009 Feb 20;384(2):260–5.   [CrossRef]   [Pubmed]    
11. Llewellyn CD, Johnson NW, Warnakulasuriya KA. Risk factors for oral cancer in newly diagnosed patients aged 45 years and younger: a case-control study in Southern England. J Oral Pathol Med 2004 Oct;33(9):525–32.   [Pubmed]    
12. Rosenberg D, Cretin S. Use of meta-analysis to evaluate tolonium chloride in oral cancer screening. Oral Surg Oral Med Oral Pathol 1989 May;67(5):621–7.   [CrossRef]   [Pubmed]    
13. Mignogna MD, Fedele S, Lo Russo L, Ruoppo E, Lo Muzio L. Costs and effectiveness in the care of patients with oral and pharyngeal cancer: analysis of a paradox. Eur J Cancer Prev 2002 Jun;11(3):205–8.   [Pubmed]    
14. Ries LAG, Kosary CL, Hankey BF, Miller BA, Clegg L, Edwards BK. eds. SEER Cancer Statistics Review, 1973-1996, Bethesda MD: National Cancer Institute; 1999.    
15. Abdo EN, Garrocho Ade A, Barbosa AA, et al. Time elapsed between the first symptoms, diagnosis and treatment of oral cancer patients in Belo Horizonte, Brazil. Med Oral Patol Oral Cir Bucal 2007 Nov 1;12(7):E469–73.   [Pubmed]    
16. Peacock ZS, Pogrel MA, Schmidt BL. Exploring the reasons for delay in treatment of oral cancer. J Am Dent Assoc 2008 Oct;139(10):1346–52.   [CrossRef]   [Pubmed]    
17. Horowitz AM, Goodman HS, Yellowitz JA, Nourjah PA. The need for health promotion in oral cancer prevention and early detection. J Public Health Dent 1996 Fall;56(6):319–30.   [CrossRef]   [Pubmed]    
18. Lawoyin JO, Aderinokun GA, Kolude B, Adekoya SM, Ogundipe BF, Ogundipe OT. Oral cancer awareness and prevalence of risk behaviours among dental patients in South-western Nigeria. Afr J Med Med Sci 2003;32(2):203–7.   [Pubmed]    
19. Adebola RA, Bamgbose BO, Adeoye JB, Amole TG. Awareness of Oral Cancer in a Northwestern Nigerian State: Assessing the Knowledge, Opinion, and Practice of Traditional Healers and Herbalists. Journal of Oral Oncology 2013;2013:1.   [CrossRef]    
20. Horowitz AM, Moon HS, Goodman HS, Yellowitz JA. Maryland adults' knowledge of oral cancer and having oral cancer examinations. J Public Health Dent 1998 Fall;58(4):281–7.   [CrossRef]   [Pubmed]    
21. Agrawal M, Pandey S, Jain S, Maitin S. Oral cancer awareness of the general public in Gorakhpur city, India. Asian Pac J Cancer Prev 2012;13(10):5195–9.   [CrossRef]   [Pubmed]    
22. Saini R, Ghani ZI, Rahman NA. The awareness of oral cancer in adult patients attending School of Dental Sciences, Universiti Sains Malaysia: a preliminary study. Singapore Dent J 2006 Dec;28(1):34–9.   [Pubmed]    
23. Ariyawardana A, Vithanaarachchi N. Awareness of oral cancer and precancer among patients attending a hospital in Sri Lanka. Asian Pac J Cancer Prev 2005 Jan-Mar;6(1):58–61.   [Pubmed]    
24. Ismail SI, Soubani M, Nimri JM, Al-Zeer AH. Cancer incidence in Jordan from 1996 to 2009--a comprehensive study. Asian Pac J Cancer Prev 2013;14(6):3527–34.   [CrossRef]   [Pubmed]    
25. Horowitz AM, Siriphant P, Sheikh A, Child WL. Perspectives of Maryland dentists on oral cancer. J Am Dent Assoc 2001 Jan;132(1):65–72.   [CrossRef]   [Pubmed]    
26. Stahl S, Meskin LH, Brown LJ. The American Dental Association's oral cancer campaign: the impact on consumers and dentists. J Am Dent Assoc 2004 Sep;135(9):1261–7.   [CrossRef]   [Pubmed]    
27. Davis JM. Tobacco cessation for the dental team: a practical guide part I: background & overview. J Contemp Dent Pract 2005 Aug 15;6(3):158–66.   [Pubmed]    
28. Desalu OO, Iseh KR, Olokoba AB, Salawu FK, Danburam A. Smokeless tobacco use in adult Nigerian population. Niger J Clin Pract 2010 Dec;13(4):382–7.   [Pubmed]    
29. Tobacco costs more than you think. Geneva: World Health Organization; 1995.    
30. Secker-Walker RH, Solomon LJ, Flynn BS, Dana GS. Comparisons of the smoking cessation counseling activities of six types of health professionals. Prev Med 1994 Nov;23(6):800–8.   [Pubmed]    
31. Warnakulasuriya S, Tilakaratne WM. Oral Medicine and Pathology: A Guide to Diagnosis and Management. 1ed. New Delhi: Jaypee Brothers Medical Publishers; 2014. p. 268–329.    
32. Mignogna MD, Fedele S. Oral cancer screening: 5 minutes to save a life. Lancet 2005 Jun 4-10;365(9475):1905–6.   [CrossRef]   [Pubmed]    
33. Zhang ZF, Morgenstern H, Spitz MR, et al. Marijuana use and increased risk of squamous cell carcinoma of the head and neck. Cancer Epidemiol Biomarkers Prev 1999 Dec;8(12):1071–8.   [Pubmed]    
34. Elango JK, Sundaram KR, Gangadharan P, et al. Factors affecting oral cancer awareness in a high-risk population in India. Asian Pac J Cancer Prev 2009 Oct-Dec;10(4):627–30.   [Pubmed]    
35. Patton LL, Agans R, Elter JR, et al. Oral cancer knowledge and examination experiences among North Carolina adults. J Public Health Dent 2004 Summer;64(3):173–80.   [CrossRef]   [Pubmed]    
36. Hobdell M, Petersen PE, Clarkson J, Johnson N. Global goals for oral health 2020. Int Dent J 2003 Oct;53(5):285–8.   [CrossRef]   [Pubmed]    
37. Shang YL. Degree distribution dynamics for disease spreading with individual awareness. J Syst Sci Complex 2015;28:96–104.